Optimization of the $\hbox{BaSnO}_{3}$ Doping Content in $\hbox{GdBa}_{2}\hbox{Cu}_{3}\hbox{O}_{7-\delta}$ Coated Conductors by Pulsed Laser Deposition

We tried to optimize the BaSnO
₃
(BSO) doping content in GdBa
₂
Cu
₃
O
_7-δ
(GdBCO) coated conductors (CCs) on CeO
₂
-buffered ion-beam assisted deposition (IBAD)-MgO templates. The BSO-doped GdBCO CCs with various x vol% ( x=0, 2, 3, 4, 5, and 6) relative to GdBCO were prepared at 800°C with the oxygen pressure of 300 mtorr by pulsed laser deposition (PLD), and their pinning properties were characterized by measuring magnetic hysteresis curves for the applied field parallel to the c-axis of GdBCO (B//c) up to 5 T and field-orientation dependence of transport critical currents for 1, 3, and 5 T at 65 and 77 K, respectively. Among all samples, a 5 vol% BSO-doped GdBCO CC exhibited the highest maximum pinning force density (F
_p,max
) values of 32.5 GN/m
³
near 4 T at 65 K and 6.5 GN/m
³
near 3.2 T at 77 K, for B//c (θ = 180
^°
), and also the highest minimum transport critical current density (Jc,min) of 0.39 MA/cm
²
at 77 K in 1 T and 0.68 MA/cm
²
at 65 K in 3 T, for θ = 120
^°
, evidencing that 5 vol% is the optimum BSO content. Observation of BSO-doped GdBCO CCs by transmission electron microscopy revealed that the effective flux pinning of BSO-doped GdBCO CC was attributed to the BSO nanorods of ~ 10-nm diameters roughly aligned along the c-axis of the GdBCO matrix.